This invention is directed to a method for recoating a substrate previously coated with a basecoat/topcoat system in which the topcoat composition comprises a fluorinated organosilane polymer. In particular, this invention is directed to a method for obtaining recoat adhesion, especially during in-line and end-of-line repair of the finish of an automobile or truck during their original manufacture.
In order to protect and preserve the aesthetic qualities of the finish on an automobile or other vehicle, it is generally known to provide a clear (unpigmented or slightly pigmented) topcoat over a colored (pigmented) basecoat, so that the basecoat remains unaffected even on prolonged exposure to the environment or weathering. This is referred to as a basecoat/topcoat or basecoat/clearcoat finish. It is also generally known that fluorocarbons provide top coatings that remain relatively dirt free under exterior use conditions and are easily cleaned when soiled, for example by washing with water. Exemplary of prior art patents disclosing top coatings containing fluorocarbon constituents are U.S. Pat. No. 4,812,337; U.S. Pat. No. 5,597,874; U.S. Pat. No. 5,605,956; U.S. Pat. No. 5,627,238; U.S. Pat. No. 5,629,372; and U.S. Pat. No. 5,705,276. Given that it is well known that consumers prefer automobiles and trucks with an exterior finish having an attractive aesthetic appearance, rapid soiling of the finish is ever more undesirable.
Commercialization of fluorinated topcoat finishes, however, has been hindered by several significant or even critical technical hurdles. For example, a commercially practical finish, among other requirements, must have adequate adhesion to repair coatings, or what is known in the art as recoat adhesion, since defects in the finish may occasionally occur during the original manufacturing process, necessitating on-site repair. Additionally, a commercially practical finish must not be problematic or difficult to apply.